Python题目2：多层菜单，进入和退出（字典）

date = {
    "1" : {
        "11" : {
            "111" : ["A","B"],
            "112" : ["C","D"],
        },
        "12" : {
            "121" : ["E","F"],
            "122" : ["G","H"]
        }
    },
    "2" :{},
    "3" :{}
}

exit_flag = False

while not exit_flag:
    for i in date:
        print(i)
    choice = input("选择进入1>>:")
    if choice in date:
        while not exit_flag:
            for i2 in date[choice]:
                print("\t",i2)
            choice2 = input("选择进入2>>:")
            if choice2 in date[choice]:
                while not exit_flag:
                    for i3 in date[choice][choice2]:
                        print("\t\t",i3)
                    choice3 = input("选择进入3>>:")
                    if choice3 in date[choice][choice2]:
                        for i4 in date[choice][choice2][choice3]:
                            print("\t\t", i4)
                        choice4 = input("最后一层，按b返回>>:")
                        if choice4 == "b":
                            pass
                        elif choice4 == "q":
                            exit_flag = True

                    if choice3 == "b":
                        break
                    elif choice3 == "q":
                        exit_flag = True
            if choice2 == "b":
                break
            elif choice2 == "q":
                exit_flag = True